1. Field of the Invention
The present disclosure generally relates to active energy absorption systems and methods of use; and more particularly to a selectively modifiable system/assembly that utilizes tethers disposed within recessed formations to drive an energy absorption member, such as an expandable honeycomb celled matrix, and to methods of absorbing energy by extending the member from the protected surface so as to intercept a projectile path prior to engaging the surface.
2. Discussion of Prior Art
Mitigating the frequency and consequences of pedestrian impact is of concern, especially when navigating urban thoroughfares and roadways with a vehicle. In the event that frontal impact with a pedestrian occurs, the upper torso and head of the pedestrian may rotate sufficiently to strike the hood and deform it sufficiently so that it may contact underlying structure proximate to the hood. An analytical simulation of force/acceleration as would occur before, during, and after a pedestrian headform strikes a vehicle hood, in accordance with IIHS (Insurance Institute for Highway Safety) testing standards and procedures, is generally provided in hidden-line type at prior art FIG. 1.
Energy absorption systems have been developed to minimize the effect of a crash event, and include both passive and active (i.e., the selective modification of the crash energy absorption characteristics of a component, assembly, or region, such as the hood) operation. Contrary to passive structures/systems, which occupy a maximum volume in the uncrushed/unstroked initial state, active systems generally expand, move, or otherwise reconfigure in response to a triggering event so as to facilitate storage in the stowed condition.
One category of active energy absorbing/occupant protection systems employs an open-celled planar member. For example, a selectively expandable honeycomb celled matrix, such as disclosed in co-owned U.S. Pat. No. 7,374,231, has been developed for use within the vehicle environment to provide impact energy management and/or occupant protection (through force and deceleration limiting) substantially parallel to the cellular axis both within and with respect to the external structure of the vehicle. These systems provide energy absorption when the vehicle encounters a projectile. With respect to pedestrian impact, for example, FIG. 1 further shows in continuous-line type a prediction from an analytical simulation of the force/acceleration experienced by a pedestrian headform, again in accordance with IIHS testing standards, when a honeycomb celled matrix is first overlaid upon the hood, so as to initially engage and absorb energy from the headform. As reflected in the graph, the matrix reduced the peak force experienced by the headform in comparison to that predicted by the analytical simulation for the case of no matrix shown in hidden-line type.
However, due to packaging concerns caused by the crowded spaces underneath the hood and more importantly the fact that analytical simulations suggest that filling empty regions under the hood would not be effective in mitigating the consequences of pedestrian impact, such measures have not been implemented with respect to the under hood region and pedestrian impact. There remains a need in the art for an improved method of implementing an active energy absorption system relative and exterior to the hood.